Our research deals principally with lipids of virulent tubercle bacilli. Cord factor and the mycobacterial sulfatides are two classes of trehalose-containing glycolipids from M. tuberculosis which are implicated in virulence and in the pathogenesis of the disease. Both substances also have antitumor activity in the line 10 strain-2 guinea pig system. A part of our studies involves synthesis of pseudo cord factors, principally based upon "trehalose dicarboxylic acids" as inexpensive substitutes for the natural product, potentially useful in tumor immunotherapy. The influence of structural changes on biological activity provides information on structure-functional relationships. The sulfatides (and other polyanionic agents as well) prevent l phagosome-lysosome fusion in cultured macrophages. The former are therefore probably functional in promoting the intracellular survival of M. tuberculosis. Our studies seek to define how polyanionic agents induce the lysosomal dysfunction and how this block may be antagonized or relieved. With conjugates of trehalose-2-sulfate to carrier proteins, immunization of rabbits may elicit antibodies wih specificity directed to the core of the sulfatide molecules. Their effect on the sulfatide-induced block will be assessed. An extension of earlier work correlating specific lipids of M. tuberculosis with phage type will embrace a search for characteristic lipids of thirty examples of certain aberrant strains (intermediate phage type).